15 February 2022

Geographic Information Systems

  • Data
  • Hardware
  • Software

Data

  • Vector
  • Raster

Vector Data

Vector data

Vector Data

Vector data

Vector Data

Vector data

Vector Data

  • ESRI Shapefiles (.shp)
  • GeoJSON (.json)
  • Comma Separated Values (.csv)
  • Keyhole Markup Language (.kml)
  • Scalable Vector Graphics (.svg)

Vector Data

  • Points
  • Polylines
  • Polygons

Vector Data: Scale

Vector data

Vector Data: Scale

Vector data

Vector Data

Raster Data

Raster data

Raster Data

Raster data

Raster Data

  • Spatial Resolution
  • Spectral Resolution

Raster Data

  • JPEG (.jpg)
  • TIFF (.tif)
  • GIF (.gif)
  • PNG (.png)

Layers

Layers

Hardware

  • memory (RAM)
  • computation (processors)
  • storage (hard drive)
  • connectivity (Internet)

GIS Software

  • read maps
  • add spatial information
  • spatial analysis
  • print maps
  • manage and transform CRS
  • GUI
  • layers
  • legends
  • servers

GIS Software

  • QGIS
  • ArcGIS
  • R
  • Python

Map Projections

  • cylindrical projections
  • conical projections
  • planar projections

Map Projections

Map projections

Map Projections

  • Angle conformity
  • Distances
  • Areas

Coordinate Reference Systems (CRS)

Projected vs. Geographic

Projected CRS: UTM

UTM

Projected CRS: UTM

  • Zone
  • northing (y) and easting (x) values in meters

Geographic CRS: WGS 84

CRS

Geographic CRS: WGS 84

  • CRS
  • datum/reference ellipsoid
  • the geoid

CRS issues

  • defining and transforming
  • measuring distance
  • measuring area
  • measuring angles

Map Production

Communication is key

Map Production

  • Title
  • Border
  • Legend
  • North Arrow / Compass Rose
  • Scale
  • Acknowledgment
  • Graticule
  • Projection Name

Maps for Visual Thinking

  • generate ideas or hypotheses
  • crude, working maps

Maps for Visual Communication

  • synthesize and present information
  • understand what you want to communicate and who is your target audience

Visual Communication

  • points, lines, polygons
  • color and pattern
  • shape
  • size
  • isolines and 3D effects

Map types

  • points
  • proportional symbols
  • choropleths
  • charts
  • isolines
  • connections

Point Maps

  • choice of symbols
  • choice of colors

Proportional Symbol Maps

  • choice of symbol
  • choice of size
  • choice of color

Choropleth Maps

  • choice of color
  • choice of pattern

Charts

  • pie
  • bar
  • graduated circle
  • line
  • density dots

Classifying color or size

  • How many classes? (4-6 as rule of thumb)
  • What type of data?
  • What does viewer need to understand?

Classification Approaches

  • Equal intervals
  • Equal counts (quantiles)
  • Equal areas
  • Natural breaks
  • Standard deviations

Modifiable Areal Unit Problem

MAUP